Department of Homeland Security officials said Wednesday it will require its law enforcement agencies to obtain a warrant before using cell phone tracking devices, a move that may shed more light into the controversial and secretive practice federal agencies fought for years to keep undisclosed.

The new policy made public Wednesday requires all agencies under the Department of Homeland Security to obtain a search warrant before deploying the cell site simulators commonly known as “Stingrays,” and to immediately delete all mobile phone data obtained after a mission, or investigation, is completed.